单选题 1 Current archaeological theory holds that the first humans in the Americas were bands of advanced Stone Age people who crossed over from what is now Siberia in Asia sometime between 12 and 30 thousand years ago. Some scientists think that these early humans crossed what is now the Bering Sea on a land bridge, a stretch of glacial ice connecting Asia and North America. Others speculate that they may have crossed that 55-mile-wide channel by boat.
2 These early humans probably migrated southward along an ice-free corridor. After several thousand years, perhaps at a pace of only ten miles every year, the migrants spread over this new land from Alaska to the tip of South America, a trail over ten thousand miles long. In South America, where the glaciers from the ice age melted first, the migrants took strong root in the fertile soil and warming climate of Patagonia. As the ice receded farther north, civilization in what is now Central America and Mexico began to take shape and flourish.

单选题 Which sentence below best expresses the essential information in the highlighted sentence in paragraph 1?

A、 Theories vary widely over how the first humans arrived in the Americas, but most state that it occurred around 30 thousand years ago.
B、 The best current theory states that between 12 and 30 thousand early humans crossed over from Siberia to North America.
C、 Human beings originated in Siberia in Asia and later formed into bands that migrated to the Americas during the Stone Age.
D、 Archaeologists believe that groups of Stone Age humans first came to the Americas from Asia about 12 to 30 thousand years ago.

【正确答案】 D

【答案解析】Current archaeological theory holds.., is paraphrased in Archaeologists believe the first humans in the Americas were bands of advanced Stone Age people.., is paraphrased in...groups of Stone Age humans first came to the Americas ...crossed over from what is now Siberia in Asia sometime between 12 and 30 thousand years ago is paraphrased in... came to the Americas from Asia about 12 to 30 thousand years ago.

单选题 Which sentence below best expresses the essential information in the highlighted sentence in paragraph 2?

A、 When the glaciers in South America melted, the climate became warmer in Patagonia, helping the people grow strong.
B、 The favorable conditions in Patagonia attracted migrants from other parts of South America, where there were still glaciers.
C、 The ice age glaciers melted earliest in South America, where the migrants settled in the warm, fertile region of Patagonia.
D、 The migrants in Patagonia in South America survived on the root crops that grew well in the fertile soil and warm climat

【正确答案】 C

【答案解析】In South America, where the glaciers from the ice age melted first.., is paraphrased in The ice age glaciers melted earliest in South America the migrants took strong root.., is paraphrased in ...the migrants settled. the fertile soil and warm climate of Patagonia is paraphrased in ... the warm, fertile region of Patagonia.